Revision - Obs 3 Flashcards
SGA vs severe SGA?
SGA: <10th centile for their gestational age
Severe SGA: <3rd centile
What 2 measurements are used to assess the fetal size?
1) Abdominal circumference
2) Estimated foetal weight
The causes of SGA can be divided into two categories.
What are they?
1) Constitutionally small
2) IUGR
The causes of fetal growth restriction can be divided into what two categories?
1) Placenta mediated –> conditions that affect transfer of nutrients across placenta
2) Non-placenta mediated –> small due to genetic or structural abnormality
When are women assessed for risk factors for SGA?
At the booking clinic
How are low-risk women for SGA monitored?
Monitoring of the symphysis fundal height (SFH) at every antenatal appointment from 24 weeks onwards to identify potential SGA.
This is plotted on a customised growth chart to assess the appropriate size for the individual woman.
From what gestation are measurements for SGA taken in low risk women?
24w gestation onwards
What is the symphysis fundal height (SFH)?
From symphisis pubic (pubic bone) to top of uterine fundus
If the symphysis fundal height is less than the 10th centile in women being monitored for SGA, what happens?
Women are booked for serial growth scans with umbilical artery doppler.
Is the induction of labour on the grounds of macrosomia advised?
No - most women with large for gestational age pregnancy will have a successful vaginal delivery.
1st line mx of shoulder dystocia?
McRobert’s manouevre (and call for help)
What does McRoberts’ manoeuvre involve?
1) flexion and abduction of the maternal hips, bringing the mother’s thighs towards her abdomen
2) this rotation increases the relative anterior-posterior angle of the pelvis and often facilitates a successful delivery.
3) can sometimes do an episiotomy: will not relieve the bony obstruction but is sometimes used to allow better access for internal manoeuvres.
Monoamniotic vs monochorionic?
Monoamniotic - 1 amniotic sac
Monochorionic - 1 placenta
N.B. best outcomes in multiple pregnancies are in diamniotic, dichorionic twin pregnancies –> each foetus has its own nutrient supply.
Define chorionicity vs amnionicity
Chorionicity - number of placentas
Amnionicity - number of amniotic sacs
How can an US be used to determine dichorionic diamniotic twins?
Dichorionic diamniotic twins have a membrane between the twins, with a lambda sign or twin peak sign
What US sign is seen in dichorionic diamniotic twins?
Lambda or twin peak sign
How can an US be used to determine monochorionic diamniotic twins?
Monochorionic diamniotic twins have a membrane between the twins, with a T sign
What US sign is seen in monochorionic diamniotic twins?
T sign
How can an US be used to determine monochorionic monoamniotic twins?
Monochorionic monoamniotic twins have no membrane separating the twins
What is a lambda sign, or twin peak sign?
Refers to a triangular appearance where the membrane between the twins meets the chorion, as the chorion blends partially into the membrane.
This indicates a dichorionic twin pregnancy (separate placentas).
What do women with multiple pregnancies require additional monitoring for?
Anaemia
Women with multiple pregnancies require additional monitoring for anaemia.
When is a FBC done?
1) Booking clinic
2) 20 weeks gestation
3) 28 weeks gestation
In women with single pregnancies, when are they screened for anaemia?
1) booking visit
2) 28w
1st line for anaemia in pregnancy?
Oral ferrous sulphate
What investigation is required in multiple pregnancy to monitor for fetal growth restriction, unequal growth and twin-twin transfusion syndrome?
Additional US scans:
1) 2 weekly scans from 16 weeks for monochorionic twins
2) 4 weekly scans from 20 weeks for dichorionic twins
When is planned birth offered for uncomplicated monochorionic monoamniotic twins?
Between 32 and 33 + 6 weeks
When is planned birth offered for uncomplicated monochorionic diamniotic twins?
Between 36 and 36 + 6 weeks
When is planned birth offered for uncomplicated dichorionic diamniotic twins?
Between 37 and 37 + 6 weeks
When is planned birth offered for triplets?
Before 35+6 weeks
AFP in Down’s syndrome screening?
Low
AFP in neural tube defects?
Raised
1st step in chickenpox exposure in pregnancy?
Check varicella antibodies if her immune status is unknown.
Blood glucose targets for self monitoring of pregnant women (pre-existing and gestational diabetes)?
Fasting –> 5.3 mmol/l
AND:
1 hour after meals –> 7.8 mmol/l, or;
2 hours after meals –> 6.4mmol/l
Quadruple screening test results in Patau’s & Edward’s vs Down’s?
Similar but in Patau & Edward’s the hCG tends to be lower, whereas in Down’s it is raised
What proteinuria defines pre-eclampsia?
> 0.3g/24h
If patient is asthmatic, 1st line medication for HTN in pregnancy?
Oral nifedipine
What are some high risk factors for pre-eclampsia?
1) Pre-existing HTN
2) Previous HTN in previous pregnancy
3) CKD
4) Diabetes type 1 or 2
5) Autoimmune conditions e.g. SLE
What are some moderate risk factors for pre-eclampsia?
1) Age >40
2) BMI >35
3) >10 years since previous pregnancy
4) Multiple pregnancy
5) First pregnancy
6) FH of pre-eclampsia
Which women would be offered aspirin as prophylaxis for pre-eclampsia?
1 high risk factor
or
> 1 moderate risk factor
Reflexes in pre-eclampsia?
hyperreflexia
Criteria for diagnosis of pre-eclampsia?
a
1) new-onset blood pressure >/= 140/90 mmHg after 20 weeks of pregnancy
AND 1 or more of the following:
a) proteinuria
b) organ dysfunction e.g. raised creatinine (creatinine ≥ 90 umol/L), elevated liver enzymes, seizures, thrombocytopenia, haemolytic anaemia
b) placental dysfunction (e.g. fetal growth restriction or abnormal Doppler studies)
What urine ACR is significant in pre-eclampsia?
> 8 mg/mmol
What urine PCR is significant in pre-eclampsia?
> 30 mg/mmol
What test is recommended in women suspected of having pre-eclampsia?
Placental growth factor testing
what is placental growth factor?
A protein released by placenta that stimulates development of new blood vessels.
Placental growth factor levels in pre-eclampsia?
Low
At what BP should pregnant women be admitted?
> 160/110 mmHg
how often is PlGF measured in potential pre-eclampsia?
Only once
How often should urinalysis be performed in women with gestational HTN (without proteinuria)?
Weekly
What scoring system are used to determine whether to admit the woman with suspected pre-eclampsia?
fullPIERS or PREP‑S
What may be used as an antihypertensive in critical care in severe pre-eclampsia or eclampsia?
IV hydralazine
How long after birth is Mg SO4 given to prevent seizures?
24h
1st line medical management of pre-eclampsia AFTER delivery?
Enalapril (ACEi)
How should fluids be managed in severe pre-eclampsia/eclampsia?
Fluid restriction
What are 2 key complications of severe pre-eclampsia (i.e. >160mmHg systolic or >110mmHg diastolic)?
1) placental abruption
2) haemorrhagic stroke
2 kidney features of pre-eclampsia?
1) proteinuria
2) oliguria
What visual defect can pre-eclampsia cause?
Scotoma
Liver features of pre-eclampsia? What is the cause?
Cause - reduced blood flow to liver
Features:
- hepatomegaly –> stretches capsule around liver –> causes RUQ/epigastric pain
- elevated liver enzymes
How can pre-eclampsia cause oedema?
1) Endothelial injury increases vascular permeability –> oedema
2) Proteinuria causes hypoalbuminaemia –> oedema
How can oedema in pre-eclampsia present?
1) Generalised oedema: legs, face & hands
2) Pulmonary oedema: cough & SOB
3) Cerebral oedema: headache, confusion & seizures
Up to how long after delivery can pre-eclampsia develop?
6 weeks
When are women routinely screened for anaemia in pregnancy?
1) booking scan
2) 20 weeks gestation
Cut off values for oral iron therapy in pregnant women?
1st trimester: <110 g/L
2nd/3rd trimester: <105 g/L
Postpartum: <100 g/L
Mx with oral ferrous sulphate
Management of folate deficiency in pregnancy?
Women with folate deficiency are started on folic acid 5mg daily.
When is a VTE risk assessment done in pregnancy?
(2)
Booking scan & again after birth
How long after birth is VTE prophylaxis continued?
6 weeks
Management of a pregnant woman with a previous VTE history?
Automatically high risk –> LMWH throughout pregnancy
How can you examine for leg swelling?
Measure circumference of calf 10cm below tibial tuberosity
What size difference between calves is significant in suspected DVT?
> 3cm difference
What 2 investigations do women with suspected PE require?
1) CXR
2) ECG
Which PE investigation carries a higher risk of breast cancer?
CTPA
Which PE investigation carries a higher risk of childhood cancer for the foetus?
VQ scan
1st line management of VTE in pregnancy?
LMWH
LMWH should be started immediately, before confirming the diagnosis in patients where DVT or PE is suspected and there is a delay in getting the scan. Treatment can be stopped when the investigations exclude the diagnosis.
How long is LMWH continued in pregnancy (after being started for established VTE)?
When the diagnosis is confirmed, LMWH is continued for the remained of pregnancy, plus six weeks postnatally, or three months in total (whichever is longer).
What does a Bishop’s score of ≥8 indicate?
that the cervix is ripe, or ‘favourable’ - there is a high chance of spontaneous labour, or response to interventions made to induce labour
Mx of suspected PE in pregnant women with a confirmed DVT?
treat with LMWH first then investigate to rule in/out
When should women with grade III/IV placenta praevia be offered c-section?
37-38w
What medication may be useful in umbilical cord prolapse to reduce uterine contractions?
Tocolytics e.g. terbutaline
T3/T4 levels during pregnancy?
In pregnancy, there is an increase in the levels of thyroxine-binding globulin (TBG).
This causes an increase in the levels of TOTAL thyroxine but does not affect the FREE thyroxine level.
When is indomethacin given for PDA?
In the postnatal period (3d-1w after birth)
Is it safe for a mother with hep B to breastfeed?
Yes
Hep B virus is not transmitted through breast milk.
Mx of newborns who are born to a hep B positive mother?
They should receive hepatitis B immunoglobulin (HBIG) and the first dose of hepatitis B vaccine within 24 hours of birth, followed by completion of the vaccination schedule.
